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Investments - Gross Unrealized Losses and Fair Value for Mortgage-Backed in Unrealized Loss Position (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Less than 12 months |  |
Gross Unrealized Losses | $ (6) | $ (228)
Estimated Fair Value | 10,815 | 16,948
12 months or more |  |
Gross Unrealized Losses | (1,509) | (6,030)
Estimated Fair Value | 113,924 | 142,184
Gross Unrealized Losses | (1,515) | (6,258)
Estimated Fair Value | 124,739 | 159,132
Mortgage-backed securities |  |
Less than 12 months |  |
Gross Unrealized Losses | (6) | (228)
Estimated Fair Value | 10,815 | 16,948
12 months or more |  |
Gross Unrealized Losses | (1,439) | (5,289)
Estimated Fair Value | 101,969 | 125,537
Gross Unrealized Losses | (1,445) | (5,517)
Estimated Fair Value | 112,784 | 142,485
Utah Housing Corporation bonds |  |
Less than 12 months |  |
Gross Unrealized Losses | 0 | 0
Estimated Fair Value | 0 | 0
12 months or more |  |
Gross Unrealized Losses | (70) | (741)
Estimated Fair Value | 11,955 | 16,647
Gross Unrealized Losses | (70) | (741)
Estimated Fair Value | 11,955 | $ 16,647
U.S. government-sponsored enterprises |  |
Less than 12 months |  |
Gross Unrealized Losses | 0 |
Estimated Fair Value | 0 |
12 months or more |  |
Gross Unrealized Losses | 0 |
Estimated Fair Value | 0 |
Gross Unrealized Losses | 0 |
Estimated Fair Value | $ 0 |

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=118942371&loc=SL82922954-210456 + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 + Details
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